Running Crew Sock - The "Original" Double Layer Anti-Blister System that Serious Runners Demand. DriWright/MicroSafe Inner Layer. DriWright Outer Layer. Flat Knit. "Thin Sock Won't Compromise Shoe Fit." Content: Inner Layer: 55% DriWright, 15% MicroSafe, 30% Nylon/Inn=Outer Layer: 68% DriWright, 28% Nylon, 4% Lycra |